Productivity Improvement of Sewer CCTV Inspection through Time Study and Route Optimization

Abstract

Closed-circuit television (CCTV) is the most widely used visual inspection method for sewers. Given the amount of public money spent on these inspections in Canada annually, productivity improvements may represent significant financial savings to the public. This paper presents a study based on several sewer mainline CCTV surveys in Edmonton, Alberta, Canada. The overall objective is to enhance sewer CCTV inspection production rate through the duration reduction of non-value added activities. The methodology includes performing a work measurement study and using a travel route optimization algorithm. The first section of the paper presents the results of the work measurement study conducted on 214 CCTV operations, as well as the calculated time allotment for each work component in the process. In the second section, an optimization technique is applied to CCTV truck movements considering the two traveling path types of road distance (actual distance traveled) and linear distance (straight distance between two points on a map) distances used to find an optimal route. As traveling to target manholes and locating those manholes are identified in the first section of the paper as the most time-consuming, non-value added activities in CCTV operations, this study investigates the application of the traveling salesman problem (TSP) as a traveling path optimization technique for daily CCTV inspections. Through the analysis of the effect of actual road distances on the CCTV inspection cycle time, this study shows that the application of a TSP solver for preplanning traveling paths can improve the inspection production rate of both daily CCTV activities and the CCTV inspection of entire neighborhoods by about 13%.